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Cavopulmonary mechanical circulatory support in Fontan patients and the need for physiologic control: A computational study with a closed-loop exercise model


Granegger, Marcus; Schweiger, Martin; Schmid Daners, Marianne; Meboldt, Mirko; Hübler, Michael (2018). Cavopulmonary mechanical circulatory support in Fontan patients and the need for physiologic control: A computational study with a closed-loop exercise model. The International Journal of Artificial Organs, 41(5):261-268.

Abstract

PURPOSE: Rotary blood pumps are a promising treatment approach for patients with a total cavopulmonary connection and a failing cardiovascular system. The aim of this study was to investigate the hemodynamic effects of cavopulmonary support using a numerical model with closed-loop baroreflex and exercise mechanisms.
METHODS: A numerical model of the univentricular cardiovascular system was developed, mimicking the hemodynamics during rest and exercise. Rotary blood pumps with different hydraulic pump characteristics (flat vs steep pressure-flow relationships) were investigated in the cavopulmonary position. Furthermore, two support modes-a constant speed setting and a physiologically controlled speed-were examined.
RESULTS: Hemodynamics without rotary blood pumps were achieved with less than 10% deviation from reported values during rest and exercise. Rotary blood pumps at constant speed improve the hemodynamics at rest, however, they constitute a hydraulic resistance during light (steep characteristics) or moderate (flat characteristics) exercise. In contrast, physiologic control increases cardiac output (moderate exercise: 8.2 vs 7.4 L/min) and reduces sympathetic activation (heart rate at moderate exercise: 111 vs 123 bpm).
CONCLUSION: In this simulation study, the necessity of an automatically controlled rotary blood pump in the cavopulmonary position was shown. A pump at constant speed might constitute an additional resistance to venous return during physical activity. Therefore, a physiologic control algorithm based on the pressure difference between the caval veins and the atrial pressure is proposed to improve hemodynamics, especially during physical activity.

Abstract

PURPOSE: Rotary blood pumps are a promising treatment approach for patients with a total cavopulmonary connection and a failing cardiovascular system. The aim of this study was to investigate the hemodynamic effects of cavopulmonary support using a numerical model with closed-loop baroreflex and exercise mechanisms.
METHODS: A numerical model of the univentricular cardiovascular system was developed, mimicking the hemodynamics during rest and exercise. Rotary blood pumps with different hydraulic pump characteristics (flat vs steep pressure-flow relationships) were investigated in the cavopulmonary position. Furthermore, two support modes-a constant speed setting and a physiologically controlled speed-were examined.
RESULTS: Hemodynamics without rotary blood pumps were achieved with less than 10% deviation from reported values during rest and exercise. Rotary blood pumps at constant speed improve the hemodynamics at rest, however, they constitute a hydraulic resistance during light (steep characteristics) or moderate (flat characteristics) exercise. In contrast, physiologic control increases cardiac output (moderate exercise: 8.2 vs 7.4 L/min) and reduces sympathetic activation (heart rate at moderate exercise: 111 vs 123 bpm).
CONCLUSION: In this simulation study, the necessity of an automatically controlled rotary blood pump in the cavopulmonary position was shown. A pump at constant speed might constitute an additional resistance to venous return during physical activity. Therefore, a physiologic control algorithm based on the pressure difference between the caval veins and the atrial pressure is proposed to improve hemodynamics, especially during physical activity.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Children's Hospital Zurich > Clinic for Surgery
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:May 2018
Deposited On:23 May 2018 13:55
Last Modified:24 Sep 2019 23:29
Publisher:Sage Publications Ltd.
ISSN:0391-3988
OA Status:Closed
Publisher DOI:https://doi.org/10.1177/0391398818762359
PubMed ID:29521133

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